In general, as shown in FIG. 1, a nuclear power generation system 1 includes a reactor 2 in which a nuclear reaction occurs, a heat exchange unit 3 carrying out cooling and heat exchange of the reactor, a power generator 7 generating electricity by using steam produced from the heat exchange unit, and a cooling unit 8 for cooling the steam. Such a nuclear power generation system further includes a steam generator 4 for generating steam.
In the nuclear power generation system, cooling water is introduced from the sea for cooling hot water passed from a turbine or cooling a heat exchanger, and waste cooling water is discharged to the sea through the outlet of the system. In general, when the cooling water introduced to the nuclear power generation system at room temperature is subjected to heat exchange for the purpose of cooling, the cooling water is heated to about 90° C. The waste cooling water is additionally cooled through a cooling system before it is discharged, so that the temperature of the discharged cooling water may not be higher than the surrounding sea water by a predetermined temperature (approximately 7° C.).
In order to provide a great amount of cooling water used for such a nuclear power generation system, sea water is used conventionally as the cooling water. In a cooling water intake apparatus having a sea water path linked thereto, adhesive marine organisms, including fish and shellfish, such as mussel and clam live and grow. Such marine organisms are introduced to the cooling water intake apparatus through the sea water path providing ideal environmental conditions of a warm temperature and low flow rate. The marine organisms introduced to the cooling water intake apparatus as described above adhere to the inner wall of the sea water path and various parts of the cooling water intake apparatus and live and grow therein, resulting in corrosion and damage of such parts. Sometimes, depending on the degree of adhesion and growth, such marine organisms partially or totally block the sea water path or the cooling water intake apparatus, resulting in serious problems, including degradation of the efficiency of a cooling water pump or failure thereof, a drop in amount of sea water introduction caused thereby, as well as corrosion or maloperation of related parts, such as a condenser or heat exchanger.
To solve the above-mentioned problems, a sea water electrolyzing apparatus 10 is installed in a nuclear power generation system as shown in FIG. 2. The sea water electrolyzing apparatus 10 carries out electrolysis of sodium chloride (NaCl) in sea water to produce sodium hypochlorite (NaOCl, also referred to as a chlorine-containing material herein), which, in turn, is injected to the water intake port to perform sterilization, thereby preventing adhesion and growth of shellfish, seaweeds, etc. to the pipelines and tubes of the heat exchanger.
Referring to FIG. 2 illustrating the sea water electrolyzing apparatus 10, a DC power source converted through a rectifier 11 is connected to each of an anode plate 12a and a cathode plate 12b. Sea water passes through the sea water electrolyzing apparatus 10, and then NaCl in sea water reacts with H2O to produce a chlorine-containing material. In other words, NaCl in sea water and H2O are electrolyzed by the DC current supplied through the rectifier to produce ions (Na, Cl, H, OH). Among such ions, Cl moves to the anode to generate chlorine gas (Cl2), while H moves to the cathode to generate hydrogen gas (H2). Na having higher reactivity than Cl presents in its ionic state and forms a bond with OH to produce NaOH, which, in turn, reacts with chlorine gas (Cl2) to produce a chlorine-containing material (NaOCl). Since the degree of electrolysis depends on the magnitude of the DC current supplied to the apparatus, it is possible to control the concentration of sodium hypochlorite.
The chlorine-containing material and hydrogen generated secondarily from the sea water electrolyzing apparatus are transferred to a storage tank 13 via a solenoid valve. The hydrogen gas at the top of the storage tank is discharged into the air through a blower 14. In other words, currently, in the sea water electrolyzing apparatus, waste hydrogen generated secondarily from the apparatus is merely emitted to the air without recycling.
Meanwhile, upon the operation of a fuel cell, catalyst oxidation or degradation of physical properties of a Nafion membrane may occur at the anode (electrode to which hydrogen is supplied) in the fuel cell due to gases or ions other than hydrogen, such as oxygen, carbon monoxide, chlorine, etc. To solve the above-mentioned problems, there has been an attempt to use a binary or ternary catalyst as a catalyst for a fuel cell. For example, a Pt—Ru electrode has been used in direct methanol fuel cells (DMFCs). However, such an attempt is not totally successful. Particularly, the problem related to degradation of physical properties of a Nafion membrane still remains unsolved.